How Maglev Trains Operate

The evolution of mass transit has had a transformative impact on human civilization. In the 1860s, the transcontinental railroad cut the months-long journey across America down to a week. A few decades later, automobiles allowed us to travel across the country at speeds far faster than on horseback. Then, with the onset of commercial aviation during World War I, coast-to-coast travel became possible within a matter of hours. Despite these advancements, train travel in the U.S. has not significantly improved in speed over the past century. For engineers seeking the next groundbreaking transportation innovation, magnetically floating trains may hold the answer.

In the 21st century, a few nations are utilizing powerful electromagnets to develop high-speed trains, known as maglev trains. These trains hover above guideways using the fundamental principles of magnetism, replacing the traditional steel wheel and track system. With no friction from rails, these trains can achieve speeds of several hundred miles per hour.

Speed is just one of the many advantages of maglev trains. Because the trains typically don’t make contact with the track, they generate significantly less noise and vibration compared to conventional, loud trains. This reduction in vibration and friction leads to fewer mechanical issues, making maglev trains less susceptible to weather-related delays.

The earliest patents for magnetic levitation (maglev) technologies were submitted by French-born American engineer Emile Bachelet in the early 1910s. Even before that, in 1904, American professor and inventor Robert Goddard had written a paper presenting the concept of maglev levitation [source: Witschge]. It didn’t take long for engineers to begin drafting plans for train systems based on this groundbreaking concept. They envisioned a future where passengers would travel aboard magnetically powered vehicles, reaching high speeds without many of the maintenance and safety issues associated with traditional trains.

A key distinction between a maglev train and a traditional train is that maglev trains don’t use a conventional engine — the type of engine typically found in trains that pull carriages along metal tracks. Instead, the engine of a maglev train is much less conspicuous. Rather than relying on fossil fuels, the magnetic fields produced by electrified coils in the track’s guideway and walls work together to move the train forward.

If you’ve ever experimented with magnets, you’re familiar with the principle that opposite poles attract while like poles repel. This basic concept is at the heart of electromagnetic propulsion. Electromagnets share a similar trait to other magnets in that they can attract metal objects, but their magnetic force is temporary. You can easily create a small electromagnet by attaching the ends of a copper wire to the positive and negative terminals of an AA, C, or D-cell battery. This creates a small magnetic field, and once you disconnect the wire from the battery, the magnetic field disappears.

The concept behind the magnetic field in the wire-and-battery experiment is the basic principle of a maglev train system. A maglev rail system consists of three main components:

Next, let’s explore the track.

The Maglev Track

The magnetized coil running along the track, known as the guideway, pushes away the large magnets beneath the train, allowing it to levitate between 0.39 and 3.93 inches (1 to 10 centimeters) above the guideway [source: Boslaugh]. Once the train is floating, power is supplied to the coils embedded in the guideway walls, generating a magnetic field system that propels the train along the track. The current provided to the coils alternates continuously, changing the polarity of the magnetized coils. This change causes the magnetic field in front of the train to pull it forward, while the magnetic field behind it adds extra thrust, pushing it along the guideway.

Maglev trains float above the tracks, supported by a cushion of air, which eliminates friction. This lack of resistance, combined with the trains' streamlined designs, enables them to achieve remarkable speeds of over 310 mph (500 kph)—twice the speed of Amtrak's fastest commuter trains [source: Boslaugh]. For context, a Boeing 777, a long-range commercial airplane, can reach a maximum speed of around 562 mph (905 kph). Developers envision maglev trains connecting cities up to 1,000 miles (1,609 kilometers) apart. At 310 mph, you could travel from Paris to Rome in just a bit over two hours.

Some maglev trains are capable of even faster speeds. In October 2016, a Japan Railway maglev bullet train reached an astounding 374 mph (601 kph) during a test run. Such speeds inspire hope that maglev technology will be ideal for long-distance routes spanning hundreds of miles.

Both Germany and Japan have advanced maglev train technology and tested prototype models. While the core concept is similar, the German and Japanese systems differ. Germany developed the Electromagnetic Suspension (EMS) system, called Transrapid. This system utilizes magnets to suspend the train just 1/3 inch (1 centimeter) above the track, even when stationary. The train remains stable due to additional guidance magnets within the vehicle. Transrapid achieved speeds of 300 mph with passengers aboard. However, following a 2006 accident and significant cost overruns, the plans for a maglev system in Germany were abandoned in 2008 [source: DW]. Since then, maglev developments have shifted primarily to Asia.

Electrodynamic Suspension (EDS)

Japanese engineers have created a competing version of maglev trains using an Electrodynamic Suspension (EDS) system, which relies on the repelling force of magnets. The key distinction between the Japanese and German maglev technologies lies in the use of superconducting electromagnets in Japan's system. These magnets remain conductive even when the power is turned off. In contrast, the German EMS system relies on standard electromagnets that require a continuous power supply. By cooling the electromagnets to extremely low temperatures, Japan's system is more energy-efficient. However, the cooling process is expensive and increases construction and maintenance costs.

Another key difference is that Japanese maglev trains hover about 4 inches (10 centimeters) above the track. A potential disadvantage of the EDS system is that the maglev trains must travel on rubber tires until they reach a liftoff speed of approximately 93 mph (150 kph). Engineers in Japan argue that having wheels is beneficial in the event of a power failure, allowing the system to come to a gradual stop. Additionally, passengers with pacemakers would need protection from the strong magnetic fields generated by the superconducting magnets.

The Inductrack is an innovative variation of the EDS system, utilizing permanent room-temperature magnets to create the magnetic fields, instead of powered electromagnets or superconducting magnets that need cooling. The Inductrack system only uses power to accelerate the train until it levitates. In the event of a power failure, the train can decelerate smoothly and come to a stop using auxiliary wheels.

The track itself is made up of a series of electrically shorted circuits containing insulated wire. In one configuration, these circuits are arranged like rungs in a ladder. As the train moves along the track, the magnetic field repels the magnets, causing the train to levitate.

There are three versions of the Inductrack design: Inductrack I, Inductrack II, and Inductrack III. Inductrack I is intended for high-speed applications, Inductrack II is tailored for low-speed use, and Inductrack III is meant to handle heavy cargo at slow speeds. Trains using Inductrack can levitate higher and more stably. As long as the train is moving at just a few miles per hour, it will levitate nearly an inch (2.54 centimeters) above the track. This increased gap means that complex sensing systems are unnecessary to maintain stability.

The use of permanent magnets was initially avoided because scientists believed they wouldn’t generate enough lift. However, the Inductrack design solves this by arranging magnets in a Halbach array, which concentrates the magnetic field above the array, rather than below it. The magnets are made from a neodymium-iron-boron alloy, a newer material that produces a stronger magnetic field. The Inductrack II model includes two Halbach arrays to enhance the magnetic field strength at lower speeds.

The concept of passive magnetic levitation is a key component of proposed hyperloop systems, which resemble an Inductrack-style train traveling through a sealed tube that surrounds the entire track. Hyperloops have the potential to outpace traditional maglevs by avoiding air resistance, which could allow them to reach supersonic speeds. Some believe that hyperloops could be more cost-effective than building conventional high-speed rail lines.

However, while maglev trains are a well-established technology with years of proven operation, no commercial hyperloop system has yet been built anywhere in the world [source: Davies].

Maglev Technology In Use

Although maglev transportation was first proposed over a century ago, the first commercial maglev train didn't come into existence until 1984. A low-speed maglev shuttle began operating between the United Kingdom's Birmingham International railway station and a terminal at Birmingham International Airport. Since then, several maglev projects have been initiated, paused, or outright canceled. However, there are currently six operational commercial maglev lines, all located in South Korea, Japan, and China.

Despite the speed, smoothness, and efficiency of maglev systems, one significant obstacle remains: they are incredibly costly to construct. U.S. cities like Los Angeles, Pittsburgh, and San Diego once had maglev plans in the works, but the high cost of building these systems (ranging from $50 million to $200 million per mile) has proved prohibitive, ultimately halting many proposed projects. Critics argue that maglev systems could cost up to five times more than traditional rail. However, advocates point out that operating these trains can be up to 70 percent cheaper than older rail technologies [sources: Hall, Hidekazu and Nobuo].

The failure of several high-profile projects hasn't helped matters. Old Dominion University in Virginia had hoped to introduce a super shuttle to transport students across campus starting in the fall of 2002. However, the train only completed a few test runs and failed to reach the promised speed of 40 mph (64 kph). The train stations were dismantled in 2010, though parts of the elevated track still stand, serving as a reminder of a $16 million failure [source: Kidd].

Yet some maglev projects continue to move forward. One ambitious plan involves a 40-mile (64-kilometer) route connecting Washington D.C. and Baltimore. The project has strong support, but its estimated cost of $15 billion has raised concerns. While the price may seem absurd elsewhere, the region's severe traffic congestion and lack of space make innovative solutions necessary, and a high-speed maglev system could be the ideal option. An added benefit – this project could eventually expand to connect Washington to New York City, reducing travel times to just 60 minutes, a transformative development for commerce and travel in the Northeast [sources: Lazo, Northeast Maglev].

The maglev revolution is already in full swing across Asia. Japan is rapidly advancing a Tokyo-to-Osaka maglev route, which may be completed by 2037. Once operational, this train will reduce the nearly three-hour journey to just 67 minutes [source: Reuters].

China is exploring a multitude of maglev routes, particularly in areas with high population density that demand mass transportation. These routes won't be high-speed trains but will focus on moving large groups of people over shorter distances at slower speeds. Nonetheless, China produces all of its own maglev technology and is set to launch a third-generation commercial maglev line that can reach speeds of up to 125 mph (201 kph). Unlike older models, this new line will be completely driverless, relying on computer sensors for acceleration and braking (current maglev trains in China still require a driver) [source: Wong].

The future of maglevs in human transportation remains uncertain. Advancements in self-driving cars and air travel may hinder the widespread adoption of maglev lines. Furthermore, the hyperloop industry could potentially disrupt traditional transportation systems. Some engineers even speculate that flying cars, despite their high cost, might eventually outperform rail systems as they would not require massive infrastructure to take off.

In the next decade or two, the world may make a final decision about the role of maglev trains. They could become a key component of high-speed travel or remain as niche projects serving specific urban populations. Alternatively, they may simply fade into obscurity as a promising yet ultimately underused technology that never reached its potential.